The specific enthalpy of liquid n-hexane at 1 atm varies linearly with temperature and equals 25.8 kJ/kg at 30°C and 129.8 kJ/kg at 50°C. 

(a) Determine the equation that relates Ĥ(kJ/kg) to T(°C) and calculate the reference temperature on which the given enthalpies are based. Then derive an equation for Ĥ(T)(kJ/kg) at 1 atm. 

(b) Calculate the heat transfer rate required to cool liquid n-hexane flowing at a rate of 20 kg/min from 60°C to 25°C at a constant pressure of 1 atm. Estimate the change in specific internal energy (kJ/kg) as the n-hexane is cooled at the given conditions.